I. Field of the Invention
The present invention relates to a running command system for an unmanned vehicle and, more particularly, to a running command system for guiding to a destination the unmanned vehicle along a preset course which is not bound by specific guide members or the like.
II. Description of the Prior Art
A conventional unmanned vehicle is driven along guide wires embedded in the floor or along optical reflection tapes adhered along a predetermined course. In this system, a deviation of the unmanned vehicle from a guide member is detected, and the unmanned vehicle is steered in accordance with a correction value. The unmanned vehicle of this type is decelerated, stopped and travels from one running path to another running path in accordance with directions or instructions such as guide lines or markers installed in advance so that the unmanned vehicle is guided to the destination. Unlike the unmanned vehicle driven along guide members, the running path is occupied not only by the unmanned vehicle but also other vehicles and persons, thereby effectively utilizing the space. However, guide members are inevitably used, and a great amount of installation and maintenance cost is required, and unless special course arrangements are made beforehand the unmanned vehicle of this type cannot be used, then appropriate applications of the unmanned vehicle of this type are limited.
Several guidance systems for an unmanned vehicle without guide members have been proposed. In most of the conventional guidance systems without guide members, a conventional method for detecting a deviation of the unmanned vehicle from the guide members is replaced with a method of calculating a deviation from the running path in accordance with a rotational angle of a vehicle wheel or an angular velocity detected by a gyro. In order to correct the calculated deviation from the running path, the unmanned vehicle is automatically driven.
However, when the unmanned vehicle is guided to the destination, it is rarely guided along a simple linear running path. In practice, the unmanned vehicle must turn right or left at an intersection of several running paths, must be stopped at work position, and must be moved from the linear path to a curved path. In most of the conventional automatic guidance systems, the unmanned vehicle can be driven along a given running paths. However, stopping, turning and running mode switching which is inevitably performed during guidance of the unmanned vehicle has not been well considered up to the present.
For example, steering information such as a steering angle, a heading angle or a radius of curvature of the running path in accordance with the running distance is prepared as data. The running mode is switched by using running distance information obtained by accumulating the rotational angle of the wheel with reference to this data, so that the unmanned vehicle can be automatically steered. However, when only the steering information is used as guidance data and various types of running courses are prepared in a course network having many intersections, the steering information for all the running courses must be prepared. In other words, a great amount of data having high redundancy must be recorded, and a memory device is thus inefficiently used, resulting in inconvenience. In order to create the steering information, an operator must instruct the unmanned vehicle in all the running courses. In addition, the steering information corresponding to a running distance must be calculated in accordance with an area map and drawings.
When the running path is modified during travel of the unmanned vehicle, or the destination changes, running command instruction data must be updated. However, it is difficult to update the running command instruction data within a short period of time, thus failing to provide a flexible system.
In order to eliminate this drawback, steering information is digitized for each running path in an entire course network. During travel of the unmanned vehicle, data correspondence to a given course is formated. However, when the technique of giving control information by the steering information corresponding to the running distance is employed, this cannot represent all information necessary for a general course but is limited to a course consisting of linear and right-angled paths, thus resulting in inconvenience.
The unmanned vehicle must be able to travel along a course consisting of various paths in a complicated running course network. Although demand has arisen for facility in giving running command instructions to the unmanned vehicle, this demand has not been realized until now.
In order to effectively utilize the unmanned vehicle system, a running course can be modified from a current moving position to set a new destination so as to satisfy needs for an emergency. However, when the conventional technique is used, complicated calculations must be performed to determine the current moving position of the unmanned vehicle. As a result, according to the guidance system for switching the running mode in accordance with the accumulated running distance, complicated processing is required since the current position of the unmanned vehicle must be obtained by complicated calculations, a proper path is selected in accordance with a relationship between the current moving position and the destination, and a motion program must be created to guide the unmanned vehicle along the proper path in accordance with the running distance.